MIAMI – Tampa was among the prominent Southeast cities cited as “exceptionally vulnerable” to sea level rise, extreme heat events, hurricanes and a decreasing freshwater supply, according to the National Climate Assessment released Tuesday.

The 11-state region – home to seven major ports and fast-growing metropolitan areas that hug the coastline – is both a major producer and consumer of energy, and it’s already suffered more billion-dollar disasters than any other part of the country. Disruptions to infrastructure could spell an economic disaster for areas dependent on tourism – more than 115 million people visited Louisiana and Florida alone in 2012.

According to the report, the Southeast faces three key threats:

♦ SEA LEVEL RISE: Tampa, New Orleans, Miami, Charleston and Virginia Beach are among the most vulnerable to the impacts of sea level rise with roads, railways, ports, airports, oil and gas facilities and water supplies at low elevations. Low-lying coastal areas are increasingly prone to flooding during tropical storms and hurricanes, and the report’s authors worry that a migration of coastal residents fleeing unaffordable insurance costs may stress the social fabric in other areas. Rising waters also put more pressure on utilities, contaminating freshwater supplies with saltwater or burdening aging storm water drainage systems designed to empty into the ocean. Barrier islands protecting oil and gas production infrastructure along the Gulf Coast are expected to become increasingly vulnerable to storm surge and deterioration from rising seas, the report says.

♦ RISING TEMPERATURES: Tampa, Atlanta, Miami and New Orleans already have had increases in the number of days with temperatures above 95 degrees, and Florida has set five different monthly records since 2010: two for heat, one for cold, one for wetness and one for dryness. Higher temperatures also are expected to contribute to an increase in harmful air pollutants in the region’s 19 largest urban areas, which the report says will lead to an increase in deaths. Crops are expected to wither in hotter summers, especially when there’s a drought. In Georgia, that could mean corn harvests decline by 15 percent and wheat yields by 20 percent through 2020. Many fruit crops may need to be replaced.

♦ LESS WATER: The net freshwater supply availability is expected to decline over the next several decades, particularly in the western part of the region, as demands for water go up due to increases in population, development and agriculture. Higher sea levels will accelerate saltwater intrusion into freshwater supplies near the coast. Porous aquifers like Florida’s are particularly vulnerable – the city of Hallandale Beach has already abandoned six of eight drinking water wells due to saltwater intrusion.